The present invention relates to dumbwaiter elevating and lowering platforms and, more particularly, to motor-driven platforms for use in confined spaces and especially useful in residential applications.
The first dumbwaiters were screw drive. The current winding drum is the most popular type of drive, consisting of a drive motor connected to a gear reducer by either direct drive or V-belts. The drum winds a cable to raise the load and several limit switches are used to set the travel limits. A disc brake is used to lock and hold the input or output shafts. The drive mechanism normally mounts below the platform, limiting the lower travel unless the drive is located below ground. Also, the platform car is usually made of sheet metal that allows any spilled materials to leak down the wall, inside the hoistway. Some systems allow for mechanical operation by pulling on a rope that, through a set of pulleys on a common shaft, raises or lowers the platform car connected to a rope.
There is a need for a dumbwaiter that does not require that the drive mechanism be located below ground in order for the platform to reach the lower level of travel. Further, there is a need for a dumbwaiter that has fewer components and easier to install.
An elevating system that moves a payload container or platform from one elevation to another. Such an elevating system allows the platform to stop at predetermined positions as needed between floors of a building or residences by depressing a xe2x80x9craisexe2x80x9d, xe2x80x9clowerxe2x80x9d or xe2x80x9cstopxe2x80x9d switch. A remote control module permits operation from a location within visual sight of the switch. The lift mechanism is comprised of a low profile torque motor integral to the rotating cylinder that wraps a cable, which through a system of pulleys, raises the payload. The low profile motor allows the payload to lower to a ground position without a hole below ground for the motor and is mounted to the bottom of the tower. The payload is lowered by reversing the rotation of the motor with gravity acting on the payload. The motor incorporates an integral electromagnetic brake. Also incorporated into the low profile motor is a rotary counter that sets the stop locations of the platform without the use of limit switches in the hoist way. The container is a single piece, made of roll molded plastic. A lip surrounds the front opening and prevents spills from exiting the container and dripping down the inside walls of the hoist way.